Insulator.



B. M. LINCOLN.

INSULATOR.

APPLICATION FILED JULY I3. I914.

Patented Sept. 12, 1916.

INVENTOR Paul M. Li nm/n ATTORNEY WITNESSES:

PAUL M. LINCOLN, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR '10 WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

, INSULA'IOR.

Specification of Letters Patent. Patented Sept, 12 1916 Application filed July 13, 1914. Serial No. 850,682.

To all whom it may concern:

Be it known that I, PAUL M. Lmoomf, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have 1nvented anew and useful Improvement in Insulators, of which .the following is a specification.

.My invention relates to electrical insulators, and it has special reference to builtup insulators which are' adapted to insulate high-potential lines or conductors from supporting poles or other structures.

When a difierence of potential exists between adjacent conducting bodies, such as a line conductor and a supporting tower, the air or other interposed insulating medium is subjected to stresses by reason of the electric field produced. A field of this character may be represented by means of flux lines called electrostatic flow lines the distribution and arrangement of which are dependent upon the shapes and sizes of the conducting bodies, their spacing, the character and shape of the insulating medium,

' and the difference of potential between the bodies.

Heretofore, insulators have usually been made of porcelain or similar material and provided with corrugated surfaces or otherwise so constructed as to secure very long surface distances. It was intended that insulators' of this character, by providing longleakage paths between the conducting bodies, would substantially preclude the occurrence of surface discharges or leaka e currents between the conducting bodies. t is well known that surface discharges occur when the air adjacent to the insulating bodies is subjected to undue concentrations of potential stresses which may result from the incorrect shapes of conducting terminals or from the incorrect form of insulat ing bodies or'from both of said factors.

As disclosed in joint patent application of Messrs. K. C. Randall, S. W. Farnsworth and C. LeG. Fortescue, Serial No. 558,744, filed April 30, 1910 and assigned to the Westinghouse Electric & Manufacturing Company, the concentration of potential stresses attributed to the incorrect form of insulating bodies may be avoided by making their shapes such as to conform to the direction of flow of theelectrostatic lines of force which represent the existing electric fields between theconducting bodies.

One object of my invention is to provide an insulator which will be capable of resisting severe mechanical shocks and strains without affecting or deteriorating its insulating properties, and which will be simple and inexpensive to construct.

Another object of my invention is to provide an insulator for high-voltage conductors in which the surfaces exposed to mechanical shock or injury are madeof some strong and tough material, such as spun metal.

A still further object of my invention is to provide an insulator of the above-mentioned character in which the insulating bodies are so shaped as to conform to the electrostatic flow lines in order to utilize, to substantially its full insulating value, the air or other insulating medium in which the conducting bodies are disposed.

My invention is illustrated in the accompanying drawing in which Figure 1 is a view, partially in elevation and partially in section, of a built-up insulator embodying a form of my invention, and Fig. 2 is a sectional view of one of the metallic members embodied in my insulating structure.

In Fig. 1, I have shown the insulator as being of the suspension type of construction, but it will be understood that this insulator may be equally well adapted to serve the function of an insulating support of the usual type.

A high-potential conductor 1 is secured,

, by means of a'clamp 2, to a conducting member 3, preferably hollow, which is so shaped as to substantially resemble two spheroidal or expanded portions 4 and 5 disposed one upon the other and merged as shown in the drawing. The upper spheroidal portion 5 is of a comparatively small diameter, while the lower spheroidal portion 4 is of a comparatively large diameter. Members 6, preferably made of spun steel and having their upper portions shaped similarly to that of the member 3 and their lower portions 7 laterally extending or conically flared, are nested into one another and held securely by means of an interposed insulating or dielectric material 8.

The upper spheroidal portion 5 of the member 3 and of each of the members projects into and is surrounded by the adjacently disposed spheroidal portion 4. As shown in Fig. 2, the diameter of the open ing 9 in each of the members 6 is slightly larger than the externalv diameter of the upper spheroidal portion 5 in order to permit the portion 5 to be'con'centrically disposed in the adjacent portion 4 of the succeeding member when building up my insulating structure. -After a sufiicient number of members 6 have been nested into one another, the insulating "material 8 is interposed between the portions 5 and the portions 4 into which they project. The exposed surfaces 10 of the insulating material 8 are shaped to substantially conform to the direction of the lines of force of the electric fields existing between the adjacent electrodes or conically flared conducting portions 7. This configuration of the exposed surfaces 10 of the dielectric material 8 permits the air to be utilized to its full insulating value, and therefore greatly increases the break-down potential between adjacent members 6.

I have shown the insulator 1 supported froma member 11 which embraces the merging portion between the spheroids 4 and 5 of the top member 6. Other means may be utilized for supporting the insulator, such, for instance, as a hook and eyelet upon the upper projection of the top'member 6; It will be apparent that the built-up insulator is capable of resisting high tensional stresses because the spheroidal portion 5 cannot be withdrawn from the spheroidal portion 4' Without removing the interposed insulating material 8. Of course, it is'important to avoid the formation of sharp edgesjand reentrant angles upon the surfaces of the metallic member 6 in order to avoid the occurrence of brush or corona discharges before the full break down point of the air is reached. The members 6, being made of sheet metal, therefore, readily lend themselves. to be made in accordance with the above-mentioned principle. I

Although I have shown and described a device having specific structural details, manymodifications may be effected therein within the spirit and scope of my invention, and I desire that-only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. An insulating structure comprising a plurality of superposed conducting members having double spheroidal top portions" and bottom 1 portions laterally extending therefrom, the lower spheroidal portion of each member loosely embracing the upper spheroidal portion. of the next succeeding member, and an insulating material interposed between the said members, the conducting members extending laterally be l yond the insulating bodies.

3. An insulating structure comprising a plurality of superposed conducting members having double spheroidal top portions and bottom portions laterally extending therefrom, the lower spheroidal portion of each member loosely embracing the upper spheroidal portion of the next succeeding member, and an insulating material interposed between the said members, the exposed portions of which are shaped to substantially conform to the direction of the lines of force of the electric field existing between the adjacent conducting parts, the conducting members extending laterally beyond the insulating bodies.

4. An' insulating structure comprising a plurality of superposed conducting shellmembers having a plurality 'of superposed expanded top portions and comically-flared bottom portions, the lower one of said expanded upper portions of each member. 7

loosely embracing the upper one of said expanded upper portions of the next succeeding member, and insulating bodies interposed between the conducting members.

5.v An insulating structure comprising a plurality of superposed conducting shellmembers each having a top portion expanded to a plurality of unequal diameters, and a bottom portion laterally extending from the top portion, the top portion of each -member expanded to a larger diameter loosely embracing the top portion of the next succeeding member expanded to a smaller diameter, and insulating bodies interposed between. the conducting members. 6. An insulating structure comprising a, plurality ofsuperposed conducting members having expanded top portions of unequal diameters, and bottom portions laterally extending-therefrom, one of the expanded top portions of each member'loosely embraclng one of the expanded top portions of the next succeeding member, and insulatmg material-interposed between the said members, the exposed portions of which are shaped to substantially conform to the direction of the lines of force of the electric field existing between the. djacent conducting'parts.

7. An insulating structure comprising a ducting parts, the conducting members explurality of superposed conducting members tending laterally beyond the insulating having expanded top portions of unequal bodies. diameters, and bottom portions laterally ex- In testimony whereof I have hereunto 5 5 tending therefrom, one of the expanded top subscribed my name this 6th day of July,

portions of each member loosely embracing 19H. one ofthe top portions of the next succeed- PAUL M LINCOLN ing member, the exposed portions of which are shaped to substantially conform to the Witnesses:

10 direction of the lines of force of the dielec- A. L. HARVEY, trio field existing between the adjacent con- B. B. Hmns. 

